Patient Education
TKA Glossary
The Words Behind Your Recovery
Over 40 knee replacement and recovery terms explained in plain language — written for patients, not textbooks.
Try the Free Knee Angle Test →AdhesionCondition
Bands of scar tissue that form between tissues and organs, sometimes causing them to stick together.
After TKA, adhesions can form in the knee joint and limit your range of motion. This is one reason early and consistent physical therapy is so important.
Ankle PumpsExercise
A simple exercise where you repeatedly flex and point your foot, moving your ankle up and down.
You'll start these within hours of surgery. They help maintain blood flow in your lower legs and reduce the risk of blood clots (DVT). Aim for 10–20 reps every hour while awake.
ArthrofibrosisCondition
Excessive scar tissue formation inside the knee joint that restricts movement.
This is one of the most common complications after TKA. It's the reason your surgical team pushes early, aggressive ROM work. If caught early, it's treatable — but prevention is much easier than correction.
Bilateral TKASurgical
A total knee replacement performed on both knees, either during the same surgery or in two separate procedures.
This is less common than staged (one knee at a time) replacements. Recovery is more demanding but means only one rehabilitation period.
Bone Cement (PMMA)Surgical
Polymethyl methacrylate — a fast-setting medical adhesive used to anchor the implant components to your existing bone.
The cement sets within minutes during surgery and allows you to bear weight on your new knee almost immediately.
Continuous Passive Motion (CPM)Rehab
A motorized device that slowly moves your knee through a set range of motion while you rest.
CPM machines were once standard after TKA but are now less commonly used. Research suggests active exercises may be equally or more effective. Your surgeon will decide if one is right for you.
ContractureCondition
A permanent tightening of muscles, tendons, or other tissues that prevents normal movement.
A flexion contracture (inability to fully straighten the knee) is one of the most important things to avoid after TKA. This is why extension exercises and prone lying are emphasized early.
CrepitusCondition
A grinding, crackling, or popping sensation or sound in the knee joint during movement.
Some crepitus after TKA is normal — it's often the new components settling in. However, if it's accompanied by pain or swelling, mention it to your surgeon.
Deep Vein Thrombosis (DVT)Condition
A blood clot that forms in a deep vein, usually in the legs.
This is one of the most serious post-surgical risks. Ankle pumps, blood thinners, and early walking all help prevent DVT.
DischargeRehab
The process of being released from the hospital or from physical therapy care.
Hospital discharge typically happens 1–2 days after surgery. PT discharge happens when you’ve met your functional goals.
EdemaCondition
Swelling caused by excess fluid trapped in your body's tissues.
Expect significant knee swelling for 3–6 months after TKA. Ice, elevation, and compression all help. Swelling is one of the biggest factors limiting your ROM progress.
ExtensionMovement
The straightening of the knee joint. Full extension is 0 degrees (a completely straight leg).
Regaining full extension is actually more important than flexion for walking normally. Your PT will likely prioritize this in the first few weeks.
FemurAnatomy
The thigh bone — the large bone that runs from your hip to your knee.
During TKA, the end of the femur is reshaped and capped with a metal component.
FlexionMovement
The bending of the knee joint. The more flexion you have, the more you can bend your knee.
You need about 90° of flexion to walk normally on flat ground, 105° to climb stairs comfortably, and 115°+ to get up from a low chair. Most TKA patients aim for 120° or more.
GaitMovement
Your walking pattern — the way you move when you walk.
After TKA, you'll likely have an altered gait while you heal. Your PT will work with you to normalize your walking pattern and eliminate compensations like limping.
GoniometerTool
A protractor-like instrument used by physical therapists to measure joint angles (range of motion).
Your PT uses this at every visit to track your progress. You can also track your ROM at home using the My Knee Recovery app, which uses your phone's camera to measure your knee angle.
Heel SlidesExercise
An exercise where you slide your heel along a surface (bed or floor) toward your buttocks to improve knee flexion.
This is one of the most important exercises in early TKA recovery. A Heel Slide Board can make this exercise easier and more effective by reducing friction.
HyperextensionMovement
Extending the knee past 0 degrees (beyond straight). Some people naturally hyperextend.
After TKA, most patients will not achieve hyperextension, and that's perfectly normal. The goal is to get to 0° (fully straight).
Ice/CryotherapyRehab
The application of cold to reduce swelling and pain.
Consistent icing (20 minutes on, 20 off) is one of the most effective tools for managing post-surgical edema and improving range of motion.
InflammationCondition
The body’s natural response to injury — redness, warmth, swelling, and pain around the surgical site.
Some inflammation is expected and necessary for healing. Excessive or prolonged inflammation may need medical attention.
Incision CareRehab
Proper management of the surgical wound, including keeping it clean and dry.
Infection is a serious complication after TKA. Follow your surgeon’s instructions carefully and report any redness, drainage, or increased warmth.
Knee Flexion ContractureCondition
The inability to fully straighten (extend) the knee — the knee stays bent even when you try to straighten it.
Even a small flexion contracture (5–10°) can significantly affect your walking pattern and cause additional strain on your other joints. Early extension work is critical.
LigamentAnatomy
A band of tough, flexible connective tissue that connects bones to other bones and stabilizes joints.
In a TKA, the ACL is removed and the PCL may be retained or substituted, depending on the implant design.
LateralAnatomy
Referring to the outer side of the knee (away from the midline of the body).
Your surgeon may describe your arthritis as “lateral compartment” or “medial compartment” to indicate which side of the knee is affected.
Manipulation Under Anesthesia (MUA)Surgical
A procedure where the surgeon forcefully bends and straightens the knee while you're under anesthesia to break up scar tissue.
MUA is typically considered when ROM progress stalls significantly (usually below 90° flexion) despite consistent therapy. It's most effective when done within 6–12 weeks of the original surgery.
MedialAnatomy
Referring to the inner side of the knee (toward the midline of the body).
Most knee arthritis occurs in the medial compartment. This is the side of the knee closest to your other leg.
Nerve BlockSurgical
An injection of local anesthetic near specific nerves to numb an area and control pain after surgery.
A nerve block can make the first 12–24 hours after surgery much more manageable, but it wears off — be ready with your pain management plan.
Osteoarthritis (OA)Condition
A degenerative joint disease where the protective cartilage that cushions the ends of your bones wears down over time.
OA is the #1 reason patients need a total knee replacement. The pain typically develops gradually over years before surgery becomes the best option.
PatellaAnatomy
The kneecap — a small, flat, triangular bone that sits in front of your knee joint.
Patellar tracking (how smoothly your kneecap glides) affects your ability to straighten and bend your knee after surgery.
Posterior Cruciate Ligament (PCL)Anatomy
A ligament inside the knee that prevents the tibia from sliding backward under the femur.
In some TKA designs (cruciate-retaining), the PCL is preserved. In others (posterior-stabilized), it's removed and its function is built into the implant design.
ProsthesisSurgical
An artificial device that replaces a missing or damaged body part — in this case, the knee implant itself.
Modern implants are designed to last 15–20+ years. Your surgeon selects the size and style based on your anatomy.
Quadriceps (Quads)Anatomy
The group of four muscles on the front of your thigh that straighten the knee and help you stand, walk, and climb stairs.
Quad strength is the single best predictor of functional recovery after TKA. If your PT seems obsessed with quad sets — that’s why.
Quad LagCondition
The inability to fully straighten the knee using your own muscle power, even though the knee can be passively straightened.
Eliminating quad lag is an early PT goal. It shows your quads are strong enough to control the knee during walking.
Quad SetExercise
An isometric exercise where you tighten your quadriceps muscle and push the back of your knee down into the bed or floor.
This is often the very first exercise you'll do after surgery. It helps "wake up" your quads and is the foundation for regaining leg control.
Range of Motion (ROM)Movement
The full movement potential of a joint — measured in degrees from full extension (straight) to full flexion (bent).
ROM is the single most tracked metric in TKA recovery. Your surgeon and PT will set ROM goals at specific milestones (e.g., 90° flexion by 2 weeks, 120° by 6 weeks).
Rehabilitation ProtocolRehab
A structured, phased plan of exercises and activities designed by your surgical team to guide your recovery.
Most TKA rehab protocols are divided into phases based on time since surgery. Each phase introduces new exercises and goals as your knee heals.
Scar TissueCondition
Fibrous tissue that forms as part of the body's natural healing process after surgery or injury.
While some scar tissue is necessary for healing, too much can limit your ROM. Scar massage and consistent stretching help keep it manageable.
Short Arc Quad (SAQ)Exercise
An exercise where you place a roll under your knee and straighten just the last 30 degrees of extension, then slowly lower.
SAQs specifically target the "terminal extension" range that's often hardest to recover after TKA. They're a step up from quad sets.
Soft TissueAnatomy
The muscles, tendons, ligaments, and other non-bone structures around the knee.
Soft tissue healing takes 6–12 weeks. This is why your surgeon and PT set ROM milestones around specific timeframes.
Straight Leg Raise (SLR)Exercise
An exercise where you lock your knee straight and lift your entire leg off the surface.
Being able to perform a straight leg raise is a key early milestone. It means your quadriceps are strong enough to control the weight of your leg.
TibiaAnatomy
The shin bone — the larger of the two bones in your lower leg, running from the knee to the ankle.
During TKA, a flat metal plate and plastic insert are placed on top of the tibia to create a smooth, new joint surface.
Total Knee Arthroplasty (TKA)Surgical
The full medical name for a total knee replacement — a surgery where damaged bone and cartilage are removed and replaced with artificial components.
Understanding this term helps you navigate medical records, insurance paperwork, and online research about your surgery.
Frequently Asked Questions
What does ROM mean after knee surgery?
ROM stands for Range of Motion. It measures how far your knee can bend (flexion) and straighten (extension), expressed in degrees. A typical recovery goal is 0° extension to 120°+ flexion.
What is a good knee flexion angle after TKA?
Most surgeons aim for at least 120° of flexion. You need about 90° for normal walking, 105° for stairs, and 115°+ to rise from a low chair. Many patients achieve 125° or more with consistent therapy.
What is arthrofibrosis and how do I prevent it?
Arthrofibrosis is excessive scar tissue formation that stiffens the joint. Prevention centers on early, consistent physical therapy, managing swelling, and hitting ROM milestones in the first 6–12 weeks after surgery.
When should I worry about swelling after knee replacement?
Some swelling is normal for 3–6 months. Contact your surgeon if swelling suddenly increases, is accompanied by redness or warmth, or if you develop calf pain (possible DVT). Ice and elevation are your best tools.
Don’t Just Guess Your Progress. Track It.
Recovery is a marathon, not a sprint. Measure your knee angle with a photo, track your ROM over time, and know exactly where you stand.